Permanent magnet motors are common, and may be used in electric vehicles. Due to the high conductivity of sintered Nd—Fe—B magnets and the slot/tooth harmonics, eddy current losses may be generated inside the magnets. This may increase the magnet temperature and can deteriorate the performance of the permanent magnets, which may lead to a corresponding reduction in efficiency of the motors. In an attempt to address these issues and to make the magnets work at elevated temperatures, high coercivity magnets may be used in motors. These magnets typically contain expensive heavy rare earth (HRE) elements, such as Tb and Dy. Reducing eddy current losses can improve the motor efficiency and the materials cost can be decreased.
To decrease eddy current losses, the resistivity of the magnets has to be increased. There are typically two approaches to increasing resistivity. The first is to increase the overall resistivity of the magnet by mixing high resistivity materials into the magnets. However, this generally leads to deterioration in the magnetic properties. The second approach is to segment the magnet by separating the Nd—Fe—B magnets into thin slices with insulating materials therebetween. Such magnets are typically produced by gluing the sliced magnets using a polymer. This magnet segmentation process involves various manufacturing steps and increases the manufacturing cost of the magnet.